Adrien Matta Natasha Timofeyuk

T-REX, MINIBALL

18N – 7 protons, 11 neutrons p1/2

1 d5/23

Low-lying states dominated by:

proton( p1/21 ) (d5/2

3 )J=5/2 or (d5/23 )J=3/2 or s1/2

1 of which the 1 and 2 from the middle configuration can’t be populated in (d,p)

these levels are confused, in the compilations

Neutron-rich pathway through light nuclei in explosive nucleosynthesis

nitrogen and carbon isotopesnear the start, and accessible

Neutron-rich pathway through light nuclei in explosive nucleosynthesis

sensitive

important

not included

included

PREVIOUS WORKCanberra data, Putt et al.(7Li,7Be)7Be* at 0.48 MeV

This reaction removes a proton, adds a neutronShould populate 3 at 0.75 MeV plus two OTHER statesapart from g.s. and 0.12 MeV

The starred peaks are the ones that contain at least in part the excited 7Be channel.The missing two peaks are the 0 and 1 from s1/2 transfer.Putt et al. identify the states as being at 0.75 and at 0.58, but we say 1.23 also possible.In the proposal, we have taken Putt et al.’s suggestion (0.58 and 0.75 peaks).

like (d,p)

Reminder: this is what was shown earlier – current EXPERIMENTAL situation, with MIRROR

MIRROR(study thesymmetry)

these levels are confused, in the compilations

Otsuka 2012

EXPERIMENT

THREE STRONG PEAKS

AS WELL AS THE 2

(THE 0 AND 1 ARE MISSINGEXCEPT IN THE ANU RESULTS)

Compare current EXPERIMENTAL situation, with THEORY

HIE-ISOLDE beam of 17N

Reaction 17N(d,p)18N5.5 MeV/A104 pps on targetT-REX plus MINIBALLGamma-ray gatingMeasure Ex and SF’s, ANC’s

THE EXPERIMENT

EXCITATION ENERGY RESOLUTION arising from the charged particle measurement

Limitations: beam spot, strip pitch, (target thickness 0.5 mg/cm2)Intensities: using predicted cross sections and spectroscopic factorsIncludes hypothetical state at neutron threshold

Deduced from measured angle and energy of proton

HOW GAMMA-RAYS WILL ALLOW THE NEAR-DEGENERATE STATES TO BE RESOLVED

Allows for Doppler correctionusing crystal segment data

40 0(d,p) centre of mass angle

(d,d)

(p,p)

WHAT WE SHOULD OBSERVE WHEN WE PLOT THE T-REX ENERGY AGAINST LAB ANGLE

PARTICLES

GAMMA-RAYS

THE TRIFOIL

TRIFOIL DETECTOR

LPC Caen

THE TRIFOIL

Angle bins: 2 degrees in c.m.

SIMULATION OF THE DIFFERENTIAL CROSS SECTION FOR ONE OF THE NEW S-WAVE STATES

Actual predicted statistics for one week of running with 0.5 mg/cm2 target

SUMMARY of REQUESTWe are requesting 27 shifts of 17N beam at 5.5 MeV/A

With this, we will perform (d,p) with the 17N beam, and study all populatedstates in 18N, using gamma-rays to select and identify the closely spaced levels.

Of this, 21 shifts are required in order to perform the (d,p) measurementWe believe that we can save time by not running on a carbon targetWe would run on a carbon target (target contaminant) if time permits

We have allowed 6 shifts for optimising the charge state to accelerate (to minimise contaminants) (extraction will use NO+ from nanoCaO+O2, + plasma)and stripping methodology (what foils, and where) to eliminate 17O

We are requesting 3 shifts for setting up with a stable pilot beam, toensure that detectors and electronics are set up correctly

We request 104 pps on the reaction target. The beam should be delivered at the T-REX + Miniball setup.

We have allowed for a 5mm diameter beam spot on target (dominates the resolution)

Klupp/Muecher @ Munich Matta @ Surrey (approx)

Reconstructed excitation energy for lowest four known states, assuming isotropic production

220 g/cm2 CD2 target, 275 keV FWHM resolution, 104 pps, HELIOS at Argonne(Calem Hoffman, Florence INPC 2013, unpublished)